Between 1986 and 1999, 8 cases of severe pneumonia due Staphylococcus aureus strains producing the Panton and Valentine leukotoxin (PVL) were referred to the French reference centre for staphylococcal toxaemia. All but one patient were children and to determine the clinical features of these pneumonia we conducted a prospective surveillance during 1999. Staphylococcal pneumonia was defined according to usual standards. All the strains were tested for the gene coding PVL, the cases associated with PVL positive strains were considered as study group. Nosocomial pneumonia were excluded. 52 cases were referred and 16 were PVL positive. These pneumonia occurred in younger patients (median age = 14.8 vs. 70.1) which were previously healthy (40% of underlying disease in control) Remarkable features were the presence of viral infection in the preceding day (75% vs. 9%), the frequency of shock (81% vs. 53%), respiratory distress (75% vs. 53%) and hemoptysia (38% vs. 3%). Leucopenia was present in 79% of cases. Mortality was higher in the PVL group (75% vs. 47%). Severe staphylococcal pneumonia with shock, leucopenia, hemoptysia and high mortality rate have been previously described in children and young adults. We established the relationship between this syndrome and the PVL production by S. aureus. We believe that viral infection constitute the prerequisite altering the respiratory epithelium which secondary allows S. aureus invasion. The necrotizing action of the PVL leads to the massive haemorrhagic necrotic pneumonia. Staphylococcal necrotizing pneumonia is a new entity which frequency is probably underestimated. Further studies are needed to determinate the prognosis factors, the role of S. aureus carriage and of viral infections. The description of this new syndrome could lead to changes in the management of staphylococcal pneumonia in children.